In U.S. Pat. No. 2,987,465 to Johnson, there is disclosed a reaction system between liquids, solids and gases in a so-called "ebullated bed" in a reaction vessel in which gases and liquids flow upwardly through a reaction zone under conditions which tend to place the contact particles in random motion. It has been found that nearly isothermal conditions result when the catalyst or contact bed is expanded at least 10%, and generally not more than 300%. It is also found that the random motion of the particles in the liquid avoids attrition and permits such control that substantially no solids are carried out of the reaction zone. In each ebullated system, variables which may be adjusted to attain the desired ebullation (random motion of the particles in the liquid) include the flow rate, density and viscosity of the liquid and the gasiform material, and the size, shape and density of the particulate material.
In such a reaction system, it is important to monitor the reaction temperatures, since conversion rates, as known to one skilled in the art, are directly proportional to reaction temperature, and in such reaction system is one important parameter of product distribution.
Thermowell assemblies, presently in use, present difficulties in inspection of the thermocouples for accuracy as well as troubleshooting, thereby reducing reliability of recorded temperature measurements. Individual thermocouples cannot be replaced during onstream use of a vessel effecting a unit process or unit operation. Additionally, replacement of such thermocouples requires removal and replacement of the full assembly, particularly in the event of a large number of thermocouple failures. Still further, thermowell designs generally were configured with a bend in the well requiring sectioning (i.e. cutting up) before removal.